In the good old days, U.S. presidents rarely mentioned Canada, outside of official visits.

Now, Donald Trump won't shut up about us.

Twice this week Mr. Trump brought up Canada, and not in a friendly way.

Canada "does not treat us right in terms of the farming and the crossing the borders," Mr. Trump grumbled in typically awkward grammar on Monday.

On Tuesday, having slept on it, he was at it again. "Canada has treated us very unfairly on timber and lumber," he complained to members of Congress at a White House trade roundtable.

Surely, Mr. Trump must have other nations to obsess about. Some of them even have nuclear warheads pointed his way, rather than two-by-fours.

Mr. Trump's tantrum may make some Canadians nostalgic for the halcyon days of cross-border flattery. During a 1961 visit to Ottawa John F. Kennedy famously said: "Geography has made us neighbours. History has made us friends. Economics has made us partners. And necessity has made us allies."

Or there was Dwight D. Eisenhower, who gushed in 1953: "It is a fact that our common frontier grows stronger every year, defended only by friendship."

Barack Obama picked up on the bf4ever thing when Prime Minister Justin Trudeau came to the White House in 2016. The two countries, Mr. Obama said, are "woven together so deeply – as societies, as economies – that it's sometimes easy to forget how truly remarkable our relationship is."

Even a cold shoulder might be better than a grumpy Trump. There was George W. Bush's speech to Congress after 9/11 when he thanked a long list of countries – but not Canada – for supporting the U.S. fight against terrorism, ignoring Canada's role in Afghanistan and in sheltering thousands of stranded airline passengers.

The key for Canada is not to overreact to every Trump eruption, says Colin Robertson, a former Canadian diplomat who worked at the Canadian embassy in Washington.

"We're always sensitive to what an American president says," points out Mr. Robertson, now a fellow at the Canadian Global Affairs Institute. "In normal times, it would be cause for alarm, but these aren't normal times."

The rhetoric may not be personal or even particularly strategic. It does, however, reflect the U.S. administration's protectionist stand on trade. And Canada's firm refusal to tilt North American free-trade deal rules in the United States's favour is getting under the President's skin.

Mr. Trump's preoccupation with Canada is a "bad omen," argues veteran Canada-U.S. watcher Christopher Sands, a professor and director of the Center for Canadian Studies at the School of Advanced International Studies at Johns Hopkins University.

"It is a bit like the House of Commons. If you get called out by name you are in trouble," Prof. Sands explains. "And Canada has taken an antagonistic approach in the NAFTA renegotiations,… putting a presidential initiative in jeopardy."

Sending a message to Canada, White House trade czar Robert Lighthizer made a point this week of saying NAFTA negotiations are going "particularly well with Mexico" – even though there is scant evidence of that.

The problem is that Canada is not bending on NAFTA, softwood lumber and a growing list of other disputes. Indeed, Ottawa recently raised the stakes by launching a sweeping attack on the U.S. trade-enforcement regime at the World Trade Organization.

Ottawa has been clear about its bottom line. It won't accept a NAFTA deal that results in less trade and puts Canada in a worse competitive position than it is now.

Canada's top trade negotiator, Steve Verheul, has been openly critical of the U.S. administration's aggressive "winner-take-all" stand at the NAFTA negotiating table.

"This is being driven to a large extent from the top, from the administration," Mr. Verheul lamented in Ottawa this week.

The good news is that Mr. Trump's attacks don't reflect how Congress and much of the rest of the United States sees Canada.

Americans consistently rank Canada as their favourite foreign country in Gallup's annual World Affairs survey. Ninety-two per cent of Americans view Canada "very" or "mostly" favourably, ahead of Britain, according to the 2017 survey. Mexico is well down the list.

The best hope for Canada is that Mr. Trump eventually loses interest and softens his NAFTA stand, bowing to push-back from Congress, the U.S. business community and many state officials.

Relax, Canada. A return to blissful obscurity may be just around the corner.